Electronic commutator



J. A. HADDAD ET AL ELECTRONIC COMMUTATOR May 1, 1951 4 Sheets-Sheet l 3m eutor$ Agent mmu E9 09 NF 0 l- Umw Filed July 9, 1948 o m50 om? y 1951 J. A. HADDAD ETAL 2,551,119

ELECTRONIC COMMUTATOR 4 Sheets-Sheet 3 Filed July 9, 1948 S I 4 n 0 n n 3 wmu 26 8T F wso ONE May 1, 1951 Filed July 9, 1948 J. A. HADDAD ET AL ELECTRONIC COMMUTATOR 4 Sheets-Sheet 4 v OFF ON OFF OFF OFF TRIGGER CIRCUITS B ON OFF OFF OFF OFF ON OFF -2 OFF OFF ON OFF s OFF'OFF OFF ON I F G- 4- FIG- .la-

Iinventors Jiwm 4. xmnw 124m 1. PMM

a figemt Patented May 1', 1951 v UNITED STATES PATENTJ OFFICE ELECTRONIC COMMUTATOR Jerrier A. Haddad, Fishkill, and Ralph L. Palmer,

Poughkeepsie, N. Y., assignors to International 7 Business Machines Corporation, New York,

N. Y., a corporation of New York Application July 9, 1948, Serial No. 37,828

This invention relates to commutators and more particularly to electronic commutators using a series of trigger circuits interconnected by coupling circuits and is of the type disclosed and referred to in the copending application of Palmer et a1. Serial No. 38,078, filed July 9, 1948.

Briefly, a coupling circuit is used to connect each trigger to the next higher one. The pulses to be counted are applied simultaneously to all the coupling circuits, only one of which is responsive thereto at any one time.' When a pulse to be counted is applied to a responsive coupling circuit, it transfers a voltage to the next higher trigger to initiate a switching of the trigger from one stable condition to the other. When the next higher trigger switches, it transfers a voltage to the next lower trigger to switch it back to the stable condition it was in, prior to being switched 14 Claims. (01. 250-27) in response to a voltage transferred from its next lower coupling circuit. At the same time the next higher trigger transfers a voltage to the next higher coupling circuit to render it responsive to the operating pulses. In this manner the stepby-step switching of the trigger continues until all triggers are in their initial stable condition or until the cycle of commutator operation is complete. Thereafter. the same cyclic pattern can be repeated in response to the pulses.

It is an object of the invention to provide a novel ring type commutator having a series of triggers each connected to the next higher one through a coupling circuit and to the next lower one through a capacitive coupling.

It is another object to provide a ring type commutator wherein a switching of each trigger causes a switching of the next lower trigger and renders the next higher coupling circuit responsive to the pulses applied to the commutator.

It is another object to provide a circuit for producing peaked pulses from square waves and means for transferring the peaked pulses simultaneously to all coupling circuits, only one of which is responsive to the peaked pulses at any given time.

It is a further object to provide a commutator responsive to a predetermined number of pulses and non-responsive thereafter, until manually reset to its original starting position.

It is a further object to provide a commutator which is non-responsive to the pulses applied to it until receipt of a pulse to render it responsive.

It is a still further object to provide a commutator non-responsive to the pulses to be count- 2 cycle of commutator operation is utilized to efiect a switching of the same trigger switched by the previous pulse to automatically reset the commutator.

It is a still further object to provide a novel switching circuit responsive to pulses applied to it for switching the stable condition of a trigger, wherein the switching of that trigger renders the switching circuit responsive to the pulses.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

" In the drawings:

Figs. 1 and 1a taken together comprise a circuit diagram showing one embodiment of the novel ring type commutator of the invention.

Fig. 2 is a circuit diagram showing one embodiment of. a novel commutator for only one cycle of commutator operation at a preselected time.

Fig. 3 is a circuit diagram showing one embodimentof novel commutator having an automatic reset.

Fig. 4 is a chart illustrating one cycle of commutator operation for the embodiment shown in Figs. 1 and 1a.

Referring more particularly to Figs. 1 and 1a, the novel commutator comprises a pulse shaping circuit generally indicated by S, four trigger circuits, A, B, C, and D, and trigger coupling stages H, I, J, and K. The shaping circuit and each trigger and coupling stage are illustrated as divided by broken vertical lines for simplicity of illustration. Each trigger includes two grid controlled tubes designated Al and A2, BI and B2, Cl and C2, and DI and D2, respectively. The tubes used are all of the same type and may, for example, be of the ordinary type having a single tube per envelope or, if desired, all tubes may be of the type having two tubes in a single envelope, such as, for example, the type designated as 6J6.

Each trigger circuit A to D has two stable conditions which are alternately assumed. In one stable condition, one tube is conductive and the other tube non-conductive, and in the other condition the conductive condition of the tubes is reversed. These two stable conditions! are referred to herein as the On and Off conditions.

The On condition is arbitrarily assumed to be when the left hand tube Al, for example, of the trigger A-is-conductive and theright hand tube tion. -The cathodes of .the tubes Al and A2 are 3 A2 is non-conductive. The. Off condition is assumed as that when the left hand tube Al. for example, of the trigger A is non-conductive and the right hand tube A2 is conductive.

In the initial or zero starting position of the commutator, the trigger A is in the On condition and the triggers .B, C and D are in the Oil condition, as indicated by the dot to the lower left side of tube Al and to the lower right side of the tubes B2, C2 and D2, respectively. This indicating scheme is followed on all .of the drawings referred to herein. The circuits of the triggers A, B, C and D are identical and the operation of the triggers will be described with reference to trigger A and the values of resistances and oapacitances employed therein. These values are given solely for the purpose of clarifying the explanation, and it is specifically understood that they may be varied considerably without departing from the principles of the invenconnected through leads Ill and II, respectively, to a zero volt line I2 and the plates of those tubes are connected-to a +l50volt line l3 through resistors l4 and I5, respectively, each of which comprises tworesistors, one of 12 k. ohms connected to the plate and the other in series therewith of 7.5 k. ohms connected to line [3. .Alead I16 connects the plate of the tube A2 to the upper end of .a voltage divider consisting of resistors .l! and 18 of 200 k. ohms each. A capacitor 1:9 of 100 micro-microfarads is con- .nected in shunt with the resistor H. The lower end of the divider is connected to a 100 volt cancel bias line 20 connected to a 100- volt bias line 2| through cancel bias switch CBS. Similarly, a lead 22 connects the plate of the tube Al to the upper end of a voltage divider consisting .of the resistors 23 and 24 of 200 k. ohms each. A capacitor 25 of 100 micro-micro- .far'ads shunts the resistor 23. The lower end of the voltage divider is connected to the --'100 volt bias line 2!.

Since the trigger A is On at the zero or starting position, the tube A2 is biased to out off by the well known trigger action so that tube Al conducts. The triggers B, C and D are Off .in the starting position, the tubes B2, C2 and D2 being conductive and the tubes Bl, Cl and DI being nonconductive. The control grids of the tubes AI, B2, C2 and D2 are connected to the cancel bias line 29 to provide for quick resetting of the commutator to the chosen starting position. I To reset the circuit to the preselected starting position, the cancel bias line 20 is disconnected from the 100 volt bias line by opening the switch CBS. When the switch CBS is opened, the voltage applied to the tubes Al, B2, C2 and D2 rises above the cutoff value and these tubes are rendered conductive irrespective of their condition immediately prior to the time when the switch CBS was opened. A smilar cancel bias system is provided for each embodiment of the invention, and in each case the purpose served is the same, the particular changes being in the connections from the control grids of the chosen tubes and the cancel bias line to determine different preselected starting conditions of the respective trigger circuits.

It is now clear that the tubes having their control grids connected to the cancelbias line 20 are conductive when the commutatotisirl the zero or preselected starting position. The closing of the switch CBS does not remove the positive bias placed on the control grid of the conducting tubes but permits them to remain conductive until the stable condition of each trigger is changed by an external means. For example, the control grid of the tube Al is placed at a potential determined by the voltage divider comprising the resistors l5, l1 and I8 connected between the +150 volt line 13 and the cancel .bias line 20. and this potential is greater than the voltage required to maintain the tube AI conductive.

In a manner which will be more fully understood hereinafter, the trigger A is switched from On to Off by the application of a negative pulse .to the control grid of the conducting tube, and is switched On by the application of a negative pulse to the plate of the non-conducting tube.

When a negative pulse is applied to the control grid of the conducting tube Al, the positive bias on that control grid is decreased and the tube Al thereupon rendered less conductive. The plate voltage of the tube Al then rises and this increased plate voltage is transferred from the plate of the tube Al to the control grid of the tube A2 through the parallel connected resistor 23 and capacitor 25. As a result, the control grid of the tube A2 is made sufficiently positive to render the tube A2 conductive. Because of this conduction, the voltage at the plate of the tube A2 decreases. This decreased voltage is transierred to the control grid of the tube Al through the parallel connected resistor H and capacitor [9 and renders the tube Al still less conductive. This cumulative action is continued until the tube Al is made non-conductive and the tube A2 reaches a state of steady conductivity. Hence, the negative pulse applied to the control grid of the tube Al switches the trigger A, as a whole, from the On to the Off condition. The trigger remains in the Off condition until a negative pulse is applied tothe plate of the non-conducting tube Al.

When such is done, its plate is pulled negative and the trigger is flipped On. The trigger remains in the On condition until a negative pulse is applied to the control grid of the tube Al The alternate application of negative pulses to the control grid and plate of the tubes Al and A2 causes the trigger to repeat the cycle of operation described above.

The shaping circuit S includes the grid controlled tubes 26 and 21 having their plates connected to the +150 volt line l3 through the resistors 28 and 29, respectively. The cathodes of the tubes 26 and 21 are connected to the zero volt line 12 through leads 30 and 3!, respectively. The plate of the tube 26 is connected through a lead 32, a capacitor 33 of micro-microfarads and a resistor 34 of 100 k. ohms to the control grid of the tube 21. The junction of the capacitor 33 and the resistor 34 is connected through a resistor 35 of 10 k. ohms to the zero volt line l2. The screen grid of the tube 21 is connected to the volt line [3 through a lead 36 and parasitic suppressor resistor 36a of 470 ohms.

The plate of the tube A2 is connected to the control grid of the tube 31 of the coupling stage H through a lead 38 and a resistor 39 of 330 k. ohms. The control grid is connected also to a 250 volt bias line 40 through a resistor 4| of 510 k. ohms anda lead 42. The cathode of the tube 31 is connected to the zero volt line-l2 through a lead 43 and the plate is connected to the plate of the tube Bl through a lead 44-. l The plate of the tube B2 is connected to the control grid of the tube 45'of the coupling stage I through a lead 46 and the resistor 39. The contro] grid is connected also to the +250 volt line 40 through the resistor 4| and a lead 49. The cathode of the tube 45 is connected to the zero volt line I2 through a lead 50 and the plate is' connected to the plate-of the tube Cl through a lead 5|.

The plate of the tube C2 is connected to the control grid of the tube 52 of the coupling stage J through a lead 53 and the resistor 39. The

control grid is connected also to the 250 volt? line :40 through the resistor 4| and a lead 56.

The cathodezof the tube 52 is connected to the a lead 58.

The plate of the tube D2 is connected to the 1-6 at random.

capacitor 33 and the resistor 34. The resistor 34 and the flow of grid current in the power tube 21 prevent the positive pulses from affecting the voltage at the plate of that tube. Hence, the negative pulse from the plate of the tube 26 impresses a negative pulse on the control grid of the tube 21 and causes a corresponding reduction in'the current flow through the tube 21 to thus produce a positive voltage pulse at its plate.

.While the input pulses to the terminal 16 are referred to as square wave pulses it is understood that it is not essential to the invention that the pulses be square waves but may be irregular positive pulses and may be impressed on the terminal The lead 14 is connected to the plate resistor 2 9 and transfers therefrom a positive pulse havcontrol grid of the tube 59 of the coupling stage 1 K through"'a' lead 60 and the resistor 39. The

cathode of the tube 59 is connected to the zero volt line |2 through a lead 64 and the plate is ing a voltage amplitude of approximately 80 volts and ranging in value from +50 volts to +130 volts. This positive pulse is transferred from the lead 14 through the capacitors 15 to the control grids of all the tubes 31, 45, 52 and 59.

The resistors I5, 39 and 4| comprise a voltage divider between the +150 volt line I3 and the -250 volt line 40. 'When the tubes A2, B2, C2

and D2 are conductive, the voltage at the junc- 1 tion of the resistors l5 and 39 will be lower than connected to the plate of the tube Al through a lead 65.

A lead 66'and a capacitor 61 of 40 micro-microfarads, in series with a 1 k. ohm resistor connect the plategresistor M of the tube BI to the contro1 grid of the tube A|. A lead 66a and a capacit' Yfila of 40 .micro-microfarads in series witlr '1 k. ohm'resistor connect the control grid of the tube A2 fto the +150 volt line i3. A lead as ir a capacitor 69 of 40 micro-microfarads, in se with a ohm resistor connect the plate resi l4 of thetube CI to the control grid of the tube" Bl. A lead 68a and a capacitor 69a of 40 micro;

microfarads in series with a 1 k. ohm resistor I connectthe control grid of the tube B2 to the ;+150 volt line l3.

resistor connect the plate resistor M of the tube DI to the control grid of the tube Cl. A lead 10a and a capacitor 1|a. of 40 micro-nucrofarads in series with a 1 k. ohm resistor connect the controlgrid'of thetube C2 to the +150 volt line 13. A lead .12 and a capacitor 'l3 of 40 micro' .microfarads in series with a 1 k. ohm resistor connectthe plate resistor M of the tube Al to the control grid of the tube DI. A lead 12a anda capacitor; 13a of 40 micro-microfarads in series with a 12k. ohm resistor connect the control'g'rid of the tube D2 to the +150 volt line l3. Arllead l4 and capacitors 15 each of micro-microfarads connect the plate resistor 29 of the tube 21 to the control grids of the tubes 31, 45,52 and 59.

The novel ring type commutator of the invention is operated :by the application of a train of plus square wave pulses to a terminal 16 con- A lead 10 and a capacitor 1| of micro-microfarads, in series with a 1 k. ohm.

when those tubes are non-conductive. When those tubes are conductive, the voltage divider action of the resistors 39 and 4| causes the voltage on the control grids of the corresponding tubes 31, 45, 52 and 59to be approximately volts. The positive pulse transferred at this time from the lead 14 is insufficient to render the tubes conductive. Hence, when each of the triggers is Off, the tube of the interstage coupling whose control gridis connected to the plate of the right hand tube of the Oil trigger is not rendered conductive by a positive pulse from the lead 14. c

When each of the triggers is On, the voltage at the plate of the right hand tube thereof is higher than when the trigger is Off. When in this condition, the voltage divider action of the resistors 5, 39 and 4| places a voltage of approximately 35 volts on the control grid of the interstage tube next following, e. g., when the trigger Ais On, the control grid of the tube 31 has a bias of 35 volts impressed upon it. If a positive pulse is applied to the control grid of an interstage tube, when that grid is at 35 volts, the tube is rendered conductive and when its control grid becomes slightly positive, the flow of grid current prevents. any further substantial increase in its voltage bias. Because of this grid current, the full amplitude of the pulse impressed on the control grid is not effective to cause a corresponding voltage change in the bias on that grid.

Now that the operation of the trigger circuits, the shaping circuit and the pulsing of the inter stage tubes has been described, a complete cycle 'of operation of this novel ring type commutator will be explained with reference to Figs. 1, 1a and 4.

Before anypulsesareapplied between the terminal l6 and the line |2, the commutator is in the zero or preselected starting condition, the triggers A, B, C, and D being On, Off, Off and Oil, respectively, as shown in Fig. 4. Thus the control grid of the tube 31 is biased to approximately 35 volts and the'control grids of the tubes 45, 52 and 59 are biased to approximately 85 -;vo 1ts 50, that the tube. ,3! only 1 can be rendered conductive in response tothe first positive pulse from the line 14.

When the first plus pulse is applied to the input terminal 76, a positive pulse is transferred from the plate resistor 29 to the lead 14 as described in connection with the operation of the shaping circuit. This positive pulse is transferred fromthe lead 14 through the capacitor 15 to' the control grid of the tube 31 and renders it conductive. the tube 31 to decrease, and this decreased voltage is" transferred through the lead 44 to the plate of BI and pulls this plate negative and the trigger B is switched On. With trigger B On and tube Bl conductive, the voltage at its plate is decreased. This decreased voltage is transferred through the lead 66, capacitor 61 and the l k; ohm resistor to the control grid of the'conductive'tube Al to render the tube Al less conductive and switch the trigger A Off. The increased plate voltage of the tube B2 when trigger Bcis On reduces the negative bias of the control grid of tube 65 to approximately -35 volts.

The increased positive voltage at the plate of the tube B2, as a result of its non-conduc- Y tion, does not cause the bias of the tube 45 to be increased to -35 volts immediately because of the delay introduced by the capacitor 75 and resistor 39. When the control grid of the tube 45 is finally biased to 35 volts, the first pulse is no longer present on the lead 14. It is readily understood that the pulses applied to the lead 14 should be of sufiiciently short duration to prevent the operation of any intestage tube'other than the one having its control grid biased as above.

When the second pulse is applied to the terminal 16, the resulting positive pulse on the lead 14 is applied through the capacitor '15 to the control grid of the tube 45 and since its grid bias is now relatively plus, this plus voltage superimposed on the relatively plus bias is enough to render that tube conductive. The resulting decreased voltage at the plate of the tube 45 is transferred through the lead to the plate of tube CI to flip trigger C On. When the trigger C switches On, the increased voltage at the plate of the tube C2 biases the control grid of the tube 52 to approximately -35 volts, and a decreased voltage at the plate of the tube Cl results in the transfer of a decreased voltage over the lead 68 and capacitor 69 to the control grid of the tube 'Bl to switch the trigger B Off.

When the third pulse is applied to the terminal 16, the resulting positive pulse on the lead .14 is applied through the capacitor 15 to the controlgrid of the tube 52 and renders that tube conductive. The resulting decreased voltage at the plate of the tube 52 is transferred through the lead 58 to the-plate of-the tube Dl to switch the trigger D On. When the trigger D switches On, the increased voltage at the plate of the tube D2 biases the control grid of the tube 59 to approximately 35 volts, and a decreased voltage at the plate of the tube DI results in the transfer of a decreased voltage over the lead and capacitor H to the control grid of the tube CI to switch the trigger C to the Off condition. 7

When the fourth pulse is applied to the terminal 16, the positive pulse on the lead 14 is applied through the capacitor to the control grid of the tube 59 and renders that tube conductive. The decreased voltage at the plate of the tube -59--is transferred through the lead 65 to the plate of tube A L to switch-the trigger A On-i- When 'th'e This causes the voltage at the plate of trigger A switches On. the increased voltage at the plate of the tube A2 biases the control grid of the tube 31 to approximately -35 volts and the decreased voltage at the plate of the tube A] results in the transfer of a decreased voltage from the resistor [4 through the lead 12, capacitor l3 and the 1 k. resistor to the control grid of the tube Di to switch the trigger D Off. The tubes and triggers of the commutator are now in the same condition they were at the zero or starting position, and one cycle of commutator operation is complete.

It is clear that throughout the operational cycle of this novel commutator only one interstage tube is conditioned to be responsive, at any given time, to the positive pulse from the lead 14. When-the conditioned interstage tube becomes responsive, it effects a switching of the next succeeding trigger circuit. The change in the plate voltage of one tube of this trigger causes the next interstage tube to be. conditioned to be responsive to positive pulses on the line 14, and the change in the plate voltage of the other tube of the trigger effects a switching of the prior trigger circuit. I

It should be noted that the connection from the control grid of the tube Al to the plate of the tube Bl provides a connection from the +150 volt line [3 to the control grid of the tube Al'. Hence, a disturbance on the line l3 may constitute sufficient unbalance of the trigger A to cause it to switch from one stable condition to the other. For this reason the capacitor 67a is pro.- vided to connect the control grid of the tube A2 to the +150 volt line [3 and thereby permit any disturbance on the line 13 to be transferred to the control grids of both the tubes Al and A2. The capacitor 610., therefore, prevents a switching of the trigger A from one stable condition to the other irrespective of the disturbance on the line l3. The capacitors tea, I la, and 13a, function similarly to the capacitor 61a and prevent a switching of the triggersB, C and D, respectively.

A complete cycle of operation of the novel electronic commutator of Figs. la and 1b is schematically shown in Fig. 4 which is deemed self-expanatory.

Referring to Fig. 2, the novel commutator comprises a shaping circuit S shown in block diagram form and capable of producing a series of sharp positive pulses on the line I4 from the positive pulses applied to the input terminal I5, the trigger circuits A, B and C and the interstage coupling circuits H and I.

The individual triggers A,B and C and the interstage coupling circuits H and'I are identical with those used in the novel commutator of Figs. land la. Connections have been made to per mit'a different mode of operation. The control grid of the tube Al is connected to the volt line 2! through the resistor 18 and the control grid of the tube A2 is connected to the cancel bias line 20 through the resistor 24. Hence, at the zero or preselected starting position, the triggers 'A, B and Care each in the Off condition.

Terminal TI is connected to the control grid of the tube A2 through a capacitor l8 and a lead 19. The plate of the tube C2 is connected through the lead 53 to the terminal 86 which exhibits the voltage changes at the plate of this $5 a terminal' 8l-- .to': which positive pulses may. be

cond-uctively'applied to switch the trigger c from;

the On to the Oif condition.

The same cancel bias switching arrangement is provided to reset the commutator to the zero or preselected startin -condition as is used with the commutator of Figs. 1 and la.

If positive pulses are applied to the lead 14 from the shaping circuit S, when the counter is in the preselected starting condition, it has no'eiTect on the stable condition of any of the triggers since the control grids of the tubes 31 and 45 are biased to approximately -85"V01ts.'

When a negative pulse is applied to the terminal 11, it is transferred through the capacitor 18 and lead 19 to the control grid of the conductive tube A2 to render it less conductive and thereby initiate the switching of the trigger A from Ofi to On. From the description of the operation of the commutator of Figs. 1 and la, it is understood that this switching of the trigger A primes the commutator to be operable in response to subsequent plus pulses from the shaping circuit, in that the bias on the control grid of the tube 31 is made relatively plus (i. e.

approximately -35 volts). v

Now, when the next plus pulse from the shaping circuit is applied to the conditioned control grid of the tube 31, it is rendered conductive and transfers a negative pulse through the lead 44 to the plate of tube Bl to switch the trigger B On. When the trigger B switches On, the increased voltage at the plate of the non-conducting tube B2 causes the control grid of the tube 45 to be biased to approximately -35 volts. The decreased voltage at the plate of the conducting tube BI is transferred through the lead 66 and capacitor 61 to the control grid of the conductive tube Al to initiate the switching of the trigger'A to the Off condition. When the trigger A switches Off, the decreased voltage at the plate of the tube A2 biases the control grid of the tube 31 to approximately -85 volts and thereby renders it non-responsive to pulses from the shaping cir-- cuit. v j

The next plus pulse from the shaping circuit renders the tube 45 conductive and a negative pulse is transferred through the lead 5! to the plate of the tube CI to switch the trigger C On. When the trigger C switches On, a decreased voltage is transferred through the lead 68 and capacitor 69 to the control grid of the conductivetube BI to switch the trigger B Off. This switchingof the trigger B biases the control grid of the tube 45 to approximately -85 volts, thereby rendering the commutator non-responsive to subsequent pulses from the shaping circuit.

The terminals 80 and 8| connected respectively to the plate of the tube C2 and the control grid of the tube Cl may be connected to circuits to form a complete ring type commutator.

On the other hand, the terminal 88 may be connected to any device responsive to the voltage at that terminal and the terminal 8| connected to a source of negative pulses to-switch the trigger Off, thus resetting the commutator to its preselected starting condition.

Hence, the commutator may be used as a single cycle device after being primed. 'For such use, an opening and closing of the cancel bias switch CBS may be necessary after each single cycle of operation to return the commutator to thestarting condition. r

, Referring to Fig. 3, the shaping circuit S and the interstage coupling circuits H and I are each identical with. the corresponding circuit of Fig. 2.

10 The trigger circuits N2, N l and N are the last three triggers of a commutator having N num-.

ber of triggers and are-identical with the triggers A, B and C, respectively, of Fig. 2. The triggers.

and interstage coupling circuits are connected as in Fig. 2. l

The terminal 85 connected through the lead 85 to the plate resistor '14 of the tube N2-| is also connected to the control grid of a tube of the next prior trigger, not shown, to switch the latter When the commutator is in the preselected starting condition, the coupling tubes 31 and 45 and the switching tube 81 are biased to approxi-' mately -85 volts, and positive pulses applied to' the lead 14 by the shaping circuit do not afiect the stable condition of any of the trigger circuits.

However, when the trigger N2 is switched from Off to On, as the result of normal counter opera--- tion,the negative bias on the control grid of the tube 31 is increased-in the plus direction to approximately -35 volts to render the tube 31 responsive to a pulse from the lead 14, r

When the next positive pulse is applied to the control grid of the tube 31, it is rendered conductive and'causes the trigger N l to switch from Off to On. When the trigger N I switches On, the bias on the control grid of the tube 45 is increased to approximately -35 volts as a result of the increased voltage at the plate of the tube At the same time, the decreased volt- N I2. age at the plate of the tube Nl-l causes a negative pulse to be transferred through the lead 66 and capacitor 61 to the control grid of the tube' N 2-| to switch the trigger N 2 from On 'toOflI'. When the trigger N2 switches Off, the control grid of the tube 31 is biased to approximately 85 volts and thereby rendered non-responsive to positive pulses from the lead 14.

When the shaping circuit applies the next positive pulse to the lead 14, the tube 45 is rendered conductive and. causes the trigger N'to switch from Oil to On.- When the trigger N switches On, a negative pulse is transferred through the lead 68 and capacitor 69 to the'control grid of the conductor tube N |--I to switch the trigger Ni from On to Ofi. When the trigger N l switches Off, the bias on the control grid of the tube 45 is decreased to approximately -85 volts, there-" by rendering it non-responsive to positive pulses from the line 14. Also, when the trigger N was switched On, the increasedvoltage at the plate of the non-conducting tube N2 causes the control grid of the tube 81 to be biased to approxi mately -35 volts.

The next positive pulse applied to the control grid of the tube 81 renders it'conductive.

The decreased voltage at the plate of the tube 81 is transferred through the leads 88 and 53 to the plate of tube N2 to switch the'trigger' N from On to oil. When the trigger N switches Off, the decreased voltage at the plate of'the' conductive tube N-2causes thecontrol grid of v the tube 81 to be biased to approximately -85 volts, thereby rendering it non-responsive to subenemas sequent positive. pulses from 'the' lead '14. and returning the commutator. to .the preselected starting condition with the. triggers N}, Ni and N in the Off condition and the tubes. 31., 4.5 and 85!; non-responsive to. the positive. pulses from the lead 14.

Briefly, the high. voltage at the. plate. of the tube N-2 resulting from the. switching On of the.- trigger N renders the switching tube. 8.1. responsive to positive pulses from the lead. '14, When. the tube 8.1 is rendered conductive in re.-. sponse to. a. positive pulse from the lead 14, it effects. a switching of the trigger N. back to the,

Gift condition. The slight time delay in the. pulse transfer caused by the capacitor 15 and resis-. tor. 39, connected between the. control. grid of the tube. 81. and, the plate of the tube N-Z, is suflicient to insure that the. trigger N, will. switch ft in, response to the conduction; of the tube. 8.1; before. the decreased voltage at the, plate. of the tube N2. renders. the. tube 81 non-conductire...

Because. of the novel automatic. resetting. effected by the switching circuit L, the com.- mutator of Fig. 3 is repeatedly operable. The novel; swit hi c rcu t may be connected to. the. ri r C o Fig. 2 in the. exact. manner that it, is connected to the trigger N of Fig. 3. In. uch. a e the terminals 80. and. BI. and. the lead. Ill; of 2; are dispensed with. Whenthe switching circuit L is so used, the trigger C is reset. automatically to the Off condition to return. the commutator to the initial preselected starting condition, This provides a commu ator for s ngle; cycle operation with an automatic reset, at the end of each cycle, each cycle of, operation be,- ing initiated from an external source at a preseiected, time.

While there have been shown and described and-pointed out the fundamental novel, features or the invention as applied to several modifica- QPSi t W be e s ood t t ari s. omisr sionsand substitutions, and, changes in th p anddejtails of the circuits illustratedand inv their operation may be made by those skilled in the art without departing. from the spirit of the invention. It is the, intention, therefore, to be ed n cated. y he. co ccf he following claims.

-Wnat. s 1e nee s=.-

e r ic. c mmu o omp isi a .e. igs. o e ec r i rig er circ its ach. ha in Oniandan Oil? condition of stability, alternately ssumed a oup ing. rc i c nnec ed. be ween. successive triggers, each. coupling circuit come. ri a r n ol e tr ode. havin its. grid. connected to one trigger and its plate connected to noth g r; a ourceo pluspulses; means for applying said. pulses simultanooufily, to. the; g ds of the triouesoi the couplin i cui s... and. n eansfor l erin h 01 .0; Off condition. of one trigger to thus alter the, bias. on the; grid of one coupling triode whereb the plus, pulses applied to all the grids will, render. only the; al-. tered bias triode responsive.

2. In an electronic commutator including a series of trigger circuits each having two grid.

controlled ubes d nand Ofi conditions of. stability alternately assumed; cancelpbias, means. for simultaneously. placing said triggers in. a. pre.-. selected one of said conditions; a. coupling circuitfor each trigger including. a grid. controlled.

triode, connectedbetween successive. triggers .andl to asource of pulses; a resistive connection from. the grid of. each triode to theplate of. one. tube of: the. next-lower trigger for priming the rid: in accordance with the condition of stability of the. trigger; a connection from the plate of; each triode. to the plate of; one tube of. the next higher trigger for switching this trigger from one con.- dition of stability to the other when the triode responds to an applied pulse. and a connection from the plate circuit of one tube of said higher trigger to the control grid of one tube of said lower trigger for effecting a switching of. the latter trigger from one condition of stability to the other when the former trigger is switched from one condition of stability to the other.

A, ring type electronic commutator including a serie of, trigger circuits each having two grid controlled tubes and two, conditions of stability alternately assumed; cancel. bias meansv for placing; said commutator in a, preselected starting position; a triode connected between successive. triggers andv tov a source of pulses, said, triode be.- in primed by a switching of, the next lower tri gerso; that when. the conductive condition of the triode is .chang.ed by an. applied. pulse the change causes a voltage to be transferred to the next higher trigger to effect a; switching thereof a connection from. the plate circuit of one tube of each trigger to the control grid of one tube of the next: lower, trigger toefiect. a switching of the latter to one, condition of; stability when the. former is switched to the other condition of stability;,

rin type. commutator comprising a. series at trigger circuits each having. two grid controlled bes and On and Off conditions of stability a1- ternately: assumed; cancel bias means for placing one; of the triggers. in. the On condition and the remaining triggersin theOfi condition; a triode for-eachtrigger having. itscontrol grid resistively connected to the. second tube. of. a. lower trigger and" its plate connected directly tothe-first tube of; the next higher trigger; a. capacitiveconnection firom the control. gridof the first tube of each trigger to the plate circuit; of thefirst tube. of the next higher trigger and a pulse source for applying. simultaneously positiye pulses. to the grids of the triodes; said triodes between the triggers being; primed when. the, next lower trigger is On and thus; rendered conductiveby pulses applied. thereto. for initiating. the. switching of the next higher trigger. to the On condition, the next higher trigger. thereby. causing the next lowertrigger. tobe switched Off,

5.; A ringtypecommutator includinga series of trigger: circuits each having two. tubes and two conditionsot stability alternately assumed; cancel bias means for. placing alLtriggersin the same plfiselected, condition. of stability at. starting; a sourceof. pulses; a. grid controlled: triode conncclicdrhetweensuccessiye trigger circuits the grid of each triodebeingprimed in one stable condition only of. itsassociatedtrigger to render it operatiye to step saidco nmutator when. an actuating. pulseis added to its primed, condition; a connection toeachof.saidgridsfor applying actuating. pulses. from said source. simultaneously to said grids and a connection for conveying a voltage change to one trigger to change the stable condition thereofto: prime the grid of the triode connected thereto to render the commutator responsiye to said applied pulses.

6; Anelectronic commutator including a series of trigger circuits each having two tubes and two conditions of stability alternately assumed; cancelibias means for placing all triggers in the same preselected condition of stability at starting; a

source of pulses;'' a gridcor'itrolled triode connected between successive trigger circuits except the last and first the grid of each triode being primed in one stable condition only of its associated trigger to render it operative to step said commutator along when an actuated pulse is added to said primed condition; a connection .from said source to each of said grids for applying the pulses simultaneously thereto and a connection for conveying a voltage change to one trigger to change "the stable condition thereof to prime the gridof the trio'deconnected thereto to render the commutator responsive to applied pulses. I 1

7. A single cycle electroniccommutator including a series of trigger circuits each having two tubes and two conditions of stability alternately assumed; cancel bias means for placing all triggers in the same preselected condition of stability at starting; a source of pulses; a grid controlled tube connected between successive trigger circuits except the last and first and primed in one condition of stability of said triggers .but unprimed in the other; a connection from said source to each of said grid controlled tubes for applying pulses simultaneously to the tubes for operating a primed tube only; a connection for conveying a voltage change to one trigger to change the stable condition thereof to prime its connected tube to render the commutator responsive to applied pulses and a tube circuit connected to the last trigger and operative by the flipping of said trigger for applying a pulse to said trigger to switch it back to the preselected condition of stability at the end of each cycle of commutator operation.

8. A single cycle commutator comprising a series of trigger circuits each having two electronic tubes and On and Off conditions of stability alternately assumed; cancel bias means for initially placing all triggers in the Off condition; a grid controlled tube having its control grid resistively connected to the second tube of each trigger, except the last, and its plate connected directly to the first tube of the next higher trigger in the series; a capacitive connection from the control grid of the first tube of each trigger, ex-

cept the last, to the plate circuit of the first tube of the next higher trigger in the series; a source of pulses; means for applying said pulses to the grid of the grid controlled tubes, said grid controlled tubes bein rendered responsive to the said pulses when the next lower trigger is On, and

when rendered conductive by said pulses initiating the switching of the next higher trigger to the On condition, the next higher trigger thereby causing the nextlower trigger to be switched Off; a capacitive connection to the second tube of the first trigger in the series for transferring a negative pulse thereto to effect a switching of the trigger to the On condition and a tube circuit connection to the last trigger in the series and operative by the flipping On of said trigger for transferring a negative pulse thereto to effect a switching of the trigger to the Off condition at the end of each cycle of commutator operation.

9. A commutator comprising a series of trigger circuits each having two electronic tubes and On and Off conditions of stability alternately assumed; cancel bias means for initially placing all triggers in the Ofi condition; a grid controlled tube having its control grid resistively connected to the second tube of each trigger, except the last, and its plate connected directly to the first tube of the next higher trigger in the series; a

capacitive .connection'from the control gridbi the first tube of each trigger, except the last, to;

the plate circuit of the first tube of the next higher trigger in the series; a source of pulses; means applying said pulses to the control grids of the grid controlled tubes, said grid controlled tubes being rendered responsive to said pulses when the next lower trigger is On and when rendered conductive by said pulses initiating the switching of the next higher trigger to the On condition, the next higher trigger thereby cause ing the next lower trigger to be switched Off; a capacitive connection to the second tube of the first trigger in the series for transferring a negative pulse thereto to effect a switching of the trigger to the On condition and a grid controlled tube having its plate connected directly to the plate of the second tube of the last trigger in the series and its control grid resistively connected thereto and to said source of pulses so that the tube is rendered responsive to said pulses when the last trigger is switched On and when rendered conductive by said pulses effects a switching of the last trigger to the Off condition.

10. An electronic commutator continuously responsive to pulses including a chain of trigger circuits each having two tubes and two conditions of stability, alternately assumed; cancel bias means for placing the counter in a preselected starting position; a grid controlled tube connected between successive trigger circuits in said chain; means for applying pulses to said grid controlled tubes, said grid controlled tubes being connected to the plate of one tube of the next lower trigger circuit and conditioned by said trigger to be responsive to the applied pulses and connected to the plate of the next higher trigger to effect a switching of the stable condition thereof when the tube responds to said pulses; a connection from each trigger to the next lower trigger to efiect a switching of the latter to one condition of stability when the former switches to the other condition of stability; a switching circuit connected to the last trigger circuit and to the source of pulses and actuated thereby to efiect a switching of the last trigger to its preselected condition of stability at starting.

11. The commutator set forth in claim 10, wherein the switching circuit includes a grid controlled tube having its plate and control grid connected to the plate of one tube of the last trigger and its control grid connected to the source of pulses so that a change in the condition of stability of said last trigger renders the tube responsive to said pulses and the subsequent receipt thereof by the tube efiects a switching of the last trigger.

12. The commutator set forth in claim 11 wherein the cancel bias means places each trigger in the same condition of stability to render the commutator non-responsive to the pulses and a connection is made to one trigger to convey a pulse thereto to change its stable condition and thereby condition its associated grid controlled tube to render the commutator responsive to the pulses.

13. In a circuit including a trigger having two tubes with the plate of each connected to a grid of the other and two conditions of stability alternately assumed, a switching circuit including a grid controlled tube having its control grid resistively connected to the plate of one tube of the trigger and its plate connected directly to the plate of the same tube of the trigger for e 15 16' switching the trigg'r to onecondition ofs'tabile- REFERENCES CITEB ity, said switching circuitvbeing rendered respona The following references are of record the si-ve to voltage pulses by the increased voltage file of this, patent: transferred. to the control grid of the; tube from one tube of the trigger when the trigger isv 5 UNITED STATES PATENTS switched tov the other condition of stability. Number Name Date 1 14. The commutator of claim 9 including a 2,306,386 Hollywood Dec. 29, 1942 capacitor connected between the control grid: of 2,324,319 Michel: July 13, 1943v the second tube of each trigger and the plate 2,366,357 Schlesinger Jan 2, 1945 supply voltage of said tubes for transferring 10 2,384,379 Ingram, Sept. 4, 1945 changes in the plate supply voltage to the secondv 2,4=l)2;989 Dickinson July 2, 1946v tube-of each trigger. 2,403,918 Grosdoffe July 16, 1946 JERRIER A. HADDAD v 2,409,689 Morton et: a1 Oct.22, 1946 RALPH'L. PALMER. 2,426,454 Johnson Aug. 26', 1947 

